I'm looking to get an open and possibly limited 2011 gun but have no idea how to get the mags for it. Specifically, I would like some 140mm STI mags with it pinned appropriately (e.g. riveted?) to limit it to 15rds. What can I do?

If I can't buy the 140mm mag tubes, then I can't buy the 126mm mag tubes because they are listed as 17rds.
Basically, I just wanted to know if I can by any of the mag tubes listed over 15rds by themselves.

Seems like the right thing to do as it's the most realistic (especially seeing the video) or just leave it as is. Zeroing out the stage seems a bit harsh when he didn't enter the score. After doing some math, his division and class standings wouldn't change.
Going from 11.46 sec to 21.46 secs would change his HF from 8.8133 to 4.7064. Divide that by the 1st place HF (Mike W.) of 6.4347 = 73.14%, which would mean 80.455 stage points out of 110. This is a loss of about 30 stage points. In Limited, he had 706 pts and 2nd place was 640. In Unclassified class, he had 656 pts and 2nd place was 597. So, it really wouldn't change anything for him...maybe a spot in the overall standings.
Personally, I'd gain about 29 stage points by doing so with my 6.3985 HF, but doens't matter to me as it wouldn't affect my standings even if it were left alone.

Yes, they did/do a lot of IDPA and some run & gun. Tomorrow is USPSA with 4 classifier and 6 field stages. Regular matches usually have only one classifier and special classifier matches usually have very little (if any) field stages. This is the best of both. Enough field stages to have some fun and enough classifier stages to get your initial classification. Round count is ~214.